Usage:
Naphthalene is used as an intermediate in the manufacture of
dyes, phthalic anhydride (production of PVC plasticisers),
tanning agents, substances used for concrete, wetting agents for
the textile industry and solvent components for pesticides (moth
repellents).

Origin/derivation:
The raw material source in Germany is coal tar which contains
some 10% naphthalene. As coke production is on the decline,
increasing use is made of petroleum-based raw materials (gasoline
pyrolysis, residual oils following pyrolysis); manufacture by
means of distillation and fractioning. The naphthalene content of
the technical product is at least 95% while the remainder is made
up of impurities such as benzo(b)thiophene (thionaphthene) or, in
petroleum-based naphthalenes, of methylindenes only.

Production figures:World production of naphthalene in 1987

Western Europe

250,000 t

Eastern Europe

200,000 t

Japan

200,000 t

USA

125,000 t

World

1,000,000 t

(figures from ULLMANN, 1991)

Toxicity

Mammals:

Rat:

LD50 1,110-9,430 mg/kg, oral

acc. BUA, 1989

Rat:

LD50 2,200 mg/kg, oral (male)

acc. BUA, 1989

Rat:

LD50 2,400 mg/kg, oral
(female)

acc. BUA, 1989

Rat:

LD50 > 2,500 mg/kg, dermal
(male,female)

acc. BUA, 1989

Rat:

LD50 > 500 mg/m3,
inhalation (8 h)

acc. BUA, 1989

Mouse:

LD50 350-710 mg/kg, oral
(female)

acc. BUA, 1989

Mouse:

LD50 533 mg/kg, oral (male)

acc. BUA, 1989

Mouse:

LD50 969-5,100 mg/kg,
subcutaneous

acc. BUA, 1989

Aquatic organisms:

American minnow:

LC50 1.3-6.9 mg/l (96 h)

acc. BUA, 1989

American minnow:

LC50 5.95-6.77 mg/l (48 h)

acc. BUA, 1989

Micropterus salmondes:

LC50 0.31-9.7 mg/l (7 d)

acc. BUA, 1989

Rainbow trout:

LC50 0.1-0.14 mg/l (96 h)

acc. BUA, 1989

Water flea:

LC50 1.79-24.1 mg/l (48 h)

acc. BUA, 1989

Characteristic effects:

Humans/mammals: Naphthalene is absorbed orally,
dermally or by way of inhalation. The toxic effect is generally
slight. Irritation of the mucous membranes and skin is extremely
rare. The absorption of a large dose causes haemolytic anaemia,
the formation of cataracts and sensitisation. Infants and
foetuses are particularly at risk. There have also been cases of
allergic reactions in humans.

The toxicity of chlorinated naphthalenes is considerably
higher (refer to the "chloronaphthalene" information
sheet).

ENVIRONMENTAL BEHAVIOUR

Water:
Naphthalene dissolves only very slightly in water and sinks as a
solid. Because of its toxic effect on aquatic organisms even at
low concentrations, naphthalene is considered as a substance
hazardous to water (In Germany: Water Hazard Class 2).

Air:
Naphthalene is produced when organic material is incompletely
combusted.

Half-life:
The half-life in the atmosphere is estimated at 7 to 24 hours
(acc. BUA, 1989).

Degradation, decomposition products:Naphthalene is degraded microbially or photochemically;
mineralisation has however not been substantiated to date under
anaerobic conditions. The primary metabolite in the organism is
naphthalene-1,2-oxide which is converted to form other compounds.
Naphthalene is oxidised in air to form alcohols (naphthols),
aldehydes and carboxylic acids.

Food chain:
There is little bioaccumulation by way of food chains.

ENVIRONMENTAL STANDARDS

Medium/ acceptor

Sector

Country/ organ.

Status

Value

Cat.

Remarks

Source

Water:

Groundw

Nl

G

0.1 µg/l

Reference

acc. TERRA TECH 6/94

Groundw

NL

L

70 µg/l

Intervention

acc. TERRA TECH 6/94

Soil:

NL

G

1 mg/kg

Reference,

Sum of 10 PAHs

acc. TERRA TECH 6/94

NL

L

40 mg/kg

Intervention,

Sum of 10 PAHs

acc. TERRA TECH 6/94

Air:

D

L

2.5 mg/m3

MIK

Long-time value

acc. BAUM, 1988

D

L

7.5 mg/m3

MIK

Short-time value

acc. BAUM, 1988

Emiss.

D

L

0.1 g/m3

mass flow > 2 g/h

acc. TA Luft, 1986

DDR

(L)

3 mg/m3

Short-time value

acc. HORN, 1989

DDR

(L)

1 mg/m3

Long-time value

acc. HORN, 1989

Workp

D

L

50 mg/m3

MAK

DFG, 1989

Workp

DDR

(L)

50 mg/m3

Short-time value

acc. HORN, 1989

Workp

DDR

(L)

20 mg/m3

Long-time value

acc. HORN, 1989

Workp

SU

(L)

20 mg/m3

PDK

acc. SORBE, 1989

Workp

USA

(L)

50 mg/m3

TWA

ACGIH, 1986

Workp

USA

(L)

75 mg/m3

STEL

ACGIH, 1986

Comparison/reference values

Medium/origin

Country

Value

Source

Surface water:

Rhine (1987)

D

< 0.01-0.03 µg/l

Lake Constance (summer, 1984)

D

0.002-0.276 µg/l

acc. BUA, 1989

acc. BUA, 1989

Air:

Urban air (1977-1984)

D

0.3-0.6 µg/m3

Kiel

D

0.009 µg/m3

acc. BUA, 1989

Tübingen

D

0.191-0.468 µg/m3

acc. BUA, 1989

Cigarette smoke (unfiltered)

0.422 µg/cigarette (main stream)

acc. BUA, 1989

acc. BUA, 1989

Assessment/comments

Naphthalene has only a slight toxic effect, but can cause
allergic reactions in humans (single case reports). Because of
the emissions from motor-vehicle exhausts, the exposure is higher
in urban areas. This can result in enhanced hypersensitivity to
other irritants. There is no information available on
carcinogenic or mutagenic potential, but the substance is a
proven hazard to foetuses.